1. Field of the Invention
The present disclosure relates generally to smart card systems, and in particular but not exclusively, relates to automatically resetting a smart card (SC) device that has entered a mute mode.
2. Description of the Related Art
Smart cards are plastic cards having an embedded integrated circuit (IC). That IC may be a logic circuit with its associated memories, a microcontroller or microprocessor with its associated memories and software, or other type of intelligence.
The IC of an SC is typically coupled to contact pads, which allow the SC to communicate or perform transactions with external devices using some type of protocol. These external devices can include an SC reader, a host personal computer (PC), SC adapters and connectors, and the like. There are also “contactless” SCs that are available.
The mechanical and electrical specifications of SCs are published by the International Standard Organization (ISO). For instance, the ISO 7816 protocol supports contact modes for SCs, while the ISO 14443 protocol supports contactless modes for SCs.
The Universal Serial Bus (USB) standard has become firmly established and has gained wide acceptance in the PC marketplace. The USB standard was developed in response to a need for a standard interface that extends the concept of “plug and play” to devices external to a PC. It has enabled users to install and remove peripheral devices external to the PC without having to open the PC case or to remove power from the PC (e.g., without having to “reboot”). The USB standard provides a low-cost, high-performance serial interface that is easy to use and readily expandable, and is supported by an increasing number of SCs that are available in the marketplace.
A USB smart card sometimes goes into a “mute” state or “mute” mode. This is a state that the SC enters when it has detected a malfunction or other abnormal condition in its operation. The abnormal condition can include, but not be limited to, a change in the SC's embedded code, a hacker attack, receipt of an unauthorized command, and the like. In the mute mode, the SC no longer responds to further commands, and more particularly, the central processing unit (CPU) or other processor of the SC does not respond to any commands or requests presented on the USB port to which it is coupled.
One technique to remove the SC from the mute mode is to perform a “hard reset” on the SC (i.e., turn the power supplied to the SC's bus off and then turn the power back on) and start over. However, with USB implementations, if such a bus reset is used to reset the SC's CPU, the enumeration, configuration, etc. of the SC on the bus is lost. Some SC applications cannot accept the lost of such data.